Multiphase Drag Modeling for Prediction of the Drag Torque Characteristics in Disengaged Wet Clutches

Pahlovy, Shahjada Ahmed; Mahmud, Syeda Faria; Kubota, Masamitsu; Ogawa, Makoto; Takakura, Norio

doi:10.4271/2014-01-2333

Cited by 39 publications

(14 citation statements)

References 6 publications

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“…Figure 2(b) shows the construction of a clutch pack which consists of several clutch disks and clutch plates, the facing of clutch disks are made with paper based materials. During the operation of a transmission, the clutch disks and clutch plates are always in relative motion to each other, therefore a viscous force is generated in automatic transmission fluid (ATF) (it is supplied to cool down the viscous heat) [3]. This shear force generates drag torque which reduces the efficiency of transmission and increases the fuel consumption of cars.…”

Section: Introductionmentioning

confidence: 99%

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Prediction of Drag Torque in a Disengaged Wet Clutch of Automatic Transmission by Analytical Modeling

et al. 2016

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In the automotive industry one of the crucial issues is reduction of CO 2 emission to protect environment. A lot of researches have been done to reduce the CO 2 emission of cars by improving efficiency of engine and engine parts or lowering the weight. However, a significant reduction of CO 2 emission of cars can also be obtained from improvement of efficiency of transmission by reducing drag torque or spin loss in disengaged wet clutch. The reduction of drag torque can be achieved by introducing groove on facing of clutch disk and further reduction can be obtained by optimizing the shape of groove. Generally, the optimum shape of groove is decided by trial and error method which requires time, making sample, conducting a lot of tests and wasting a lot of raw materials. In this research, we proposed a new analytical model to predict the drag torque characteristics of a disengaged wet clutch of transmission without making any samples and performing any tests. The feature of the model: It bases on continuity and Navier-Stokes equation, a real time visualization investigation and laminar flow. The model is validated with tests results and the comparison result shows that they are very close to each other. The significance of the model is: it captures the multiphase drag torque characteristic which changes with changing gaps, speeds and oil flow rates. Moreover, the model is a green environment friendly tool to estimate drag torque characteristics without making any samples or conducting any drag tests.

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Section: Introductionmentioning

confidence: 99%

“…In his model it was not experimentally proved that the vapor cavitation or gas cavitation was occurred. In our previous study [3], we proposed a drag torque model for wet disengaged clutches based on aeration phenomenon (air enters the oil film). For fluid flow behavior investigation, a digital camera was used previously.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Drag Torque in a Disengaged Wet Clutch of Automatic Transmission by Analytical Modeling

et al. 2016

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“…The measurement and prediction of wet clutch disengaged performance has attracted considerable attention in literature [5,6,7]. The works of Pahovly et al [5], Iqdal et al [6], Yuan et al [7] and Morris et al [8] have led to a better understanding through the use of analytical models, which consider shear and cavitation between a stationary and a rotating plate. These models typically only consider the motion of one plate, which represents only a portion of the operating conditions experienced in some applications.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Lubricant Film Separation During Codirectional and Counter-Directional Rotations of Disengaged Wet Clutch Packs

Morris

Patel

Rahnejat

2019

Journal of Fluids Engineering

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The parasitic drag losses incurred by wet clutches, used in transmission systems, can significantly affect vehicular powertrain efficiency. This paper presents a novel implicit solution for hydrodynamic parasitic drag losses of disengaged clutches. These are generated by conjunctional friction, taking into account lubricant film separation during codirectional and counter-directional disk pair rotations. Lubricant film rupture is considered through application of incipient reverse flow boundary condition, which is representative of lubricant film separation. The results point to the operating conditions at which significant power losses occur. In particular, the time efficient model is able to represent the small losses incurred during codirectional rotation of disk pairs.

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“…Reynolds equation, including lubricant inertial flow was used by Pahlovy et al [5] to investigate the influence of various radial groove designs on the efficiency of wet clutch packs. Another study investigating wet clutch packs was presented by Razzaque and Kato [6], comprising a computational fluid dynamic model to include the effect of lubricant squeeze film effect during engagement.…”

Section: Introductionmentioning

confidence: 99%

“…Investigations of power loss produced by a disengaged wet brake and clutch packs have also been conducted [4][5][6][7][8]. A simple equation to predict drag torque in wet clutches under fully laminar flow was provided by Kitabayashi et al [4] as:…”

Section: Introductionmentioning

confidence: 99%

Efficiency of disengaged wet brake packs

Leighton

Morris

Trimmer

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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Key objectives in off-highway vehicular powertrain development are fuel efficiency and environmental protection. As a result palliative measures are made to reduce parasitic frictional losses, whilst sustaining machine operational performance and reliability. A potential key contributor to the overall power loss is the rotation of disengaged wet multi-plate pack brake friction. Despite the numerous advantages of wet brake pack design, during high speed manoeuvre in highway travel or at start-up conditions significant frictional power losses occur.The addition of recessed grooves on the brake friction lining is used to dissipate heat during engagement. These complicate the prediction of performance of the system, particularly when disengaged. To characterise the losses produced by these components, a combined numerical and experimental approach is required. This paper presents a Reynolds-based numerical model including the effect of fluid inertia and squeeze film transience for prediction of performance of wet brake systems. Model predictions are compared with very detailed combined Navier-Stokes and Raleigh-Plesset fluid dynamics analysis to ascertain its degree of conformity to representative physical operating conditions, as well the use of a developed experimental rig. The combined numerical and experimental approach is used to predict significant losses produced during various operating conditions. It is shown that cavitation becomes significant at low temperatures due to micro-hydrodynamic action, enhanced by high fluid viscosity. The magnitude of the losses for these components under various operating conditions is presented.The combined numerical-experimental study of wet multi-plate brakes of off-highway vehicles with cavitation flow dynamics has not hitherto been reported in literature.2

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Multiphase Drag Modeling for Prediction of the Drag Torque Characteristics in Disengaged Wet Clutches

Cited by 39 publications

References 6 publications

Prediction of Drag Torque in a Disengaged Wet Clutch of Automatic Transmission by Analytical Modeling

Prediction of Drag Torque in a Disengaged Wet Clutch of Automatic Transmission by Analytical Modeling

Hydrodynamic Lubricant Film Separation During Codirectional and Counter-Directional Rotations of Disengaged Wet Clutch Packs

Efficiency of disengaged wet brake packs

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